The Bernese Periacetabular Osteotomy (PAO) has become the established method for treating developmental dysplasia of the hip. In the 1990s, the surgical technique was modified to avoid postoperative cam impingement due to uncorrected head neck offset or pincer impingement due to acetabular retroversion after reorientation. The goal of the study was to compare the survivorship of two series of PAOs with and without the modifications of the surgical technique and to calculate predictive factors for a poor outcome. A retrospective, comparative study of two consecutive series of PAOs with a minimum follow-up of 10 years was carried out. Series A included 75 PAOs performed between 1984 and 1987 and represent the first cases of PAO. Series B included 90 hips that underwent PAO between 1997 and 2000. In this series, emphasis was put on an optimal acetabular version next to the correction of the lateral coverage. Additionally, a concomitant arthrotomy was performed in every hip to check impingement-free range of motion after reorientation and in 50 hips (56%) an additional offset correction was performed. Survivorship analyses according to Kaplan and Meier were carried out and the endpoint was defined as conversion to a total hip arthroplasty, progression of osteoarthritis, or a Merle d'Aubign score 14. Predictive factors for poor outcome were calculated using the Cox-regression analysis. The cumulative 10-year survivorship of Series A was significantly decreased (77%; 95%-confidence interval [CI] 72–82%) compared to Series B (86%; 95%-CI 82–89%, p=0.005). Hips with an aspherical head showed a significantly increased survivorship if a concomitant offset correction was performed intraoperatively (90% [95%-CI 86–94%] versus 77% [95%-CI 71–82%], p=0.003). Preoperative factors predicting poor outcome included a high age at surgery, a Merle d'Aubign score 14, a positive impingement test, a positive Trendelenburg sign, limp, an increased grade of osteoarthritis according to Tönnis, and (sub-) luxation of the femoral head (Severin > 3). In addition, predictive factors related to the three dimensional orientation of the acetabular fragment were identified. These included total, anterior, and posterior acetabular over-coverage or under-coverage, acetabular retroversion or excessive anteversion, a lateral center edge angle < 22 °, an acetabular index > 14 °, and no offset correction in aspherical femoral heads. A good long term result after PAO mainly depends on optimal three-dimensional orientation of the acetabulum and impingement-free range of motion with correction of an aspherical head neck junction if necessary

Several studies have reported the assessment of the femoral head coverage on plane radiograph and CT data in supine position, though young patients with the dysplastic hip often have symptoms during activities such as standing, walking, and running. On the other hand, some investigators have used a method of CT which allows standardization of the femoral head coverage against an anterior pelvic plane based on the anterior superior iliac spines and the pubic tubercle. We believe both the weight-bearing position and the standardized position to be more relevant for diagnosis and preoperative surgical assessment. So, we show the femoral head coverage in standardized position using 3D-CT method and in weight-bearing position using the plane radiograph and the three-dimensional lower extremity alignment assessment system before and after Curved periacetabular osteotomy (CPO). Especially the covered volume of the femoral head, a new concept, using the three-dimensional lower extremity alignment assessment system which differs from the affected area and is measured by the ratio of the covered area in the medial part of the line connecting the anterior point of the acetabulum with the posterior to the femoral head area in each axial slice, superior slices than the slice passing through the femoral head center, obtained from the reproduced 3D model of the pelvis and the femur in standing position allows us to integrate various measurements reported by past researchers. We studied the consecutive 16 patients treated with CPO. In standardized position the sagittal sectional angles on the slice passing through the femoral head center using 3D-CT method gave us how the anterior, lateral, and posterior coverage was lack compared with normal subjects and whether the adequate transfer of the rotated fragment was performed after operation. The covered volume of the femoral head decides generally the deficiency or the adequateness. In standing position, though the pelvic tilt changes, the femoral head coverage on plane radiograph, representation by the CE angle, the VCA angle, AHI and ARO, was significantly improved, and the covered volume of the femoral head was significantly improved from 25.7% preoperatively to 51.1% postoperatively. Our study showed the improvement of the femoral head coverage, including the covered volume of the femoral head as a new concept, after CPO in weight-bearing and standardized position. The morphological and functional assessment of the femoral head coverage on both pre- and post-CPO should be performed because we can obtain the objective information in standardized position and the femoral head coverage in standing position is closely connected with the pain

INTRODUCTION. Management of neglected residually displaced acetabular fractures is a big challenge. ORIF is often doomed to failure so a primary total hip replacement is usually kept in mind as a method of choice. However THR is a technically difficult and results are quiet unpredictable. OBJECTIVE. To present our experience with THR in maltreated grossly displaced acetabular fractures and to discuss operative technique and prognostic factors in that complicated surgery. MATERIAL. THR was applied in 14 patients (11 males and 3 females, mean age 51 years) with at least three-months old and significantly displaced acetabular fractures. In 12 cases preceding treatment was conservative, and in 2 it was operative. Fracture nonunion was recognized in 5 cases, old hip dislocation in 4 and protusion in 3. Large interfragmentary gaps and local bone defect were detected in almost all cases. METHOD. THR was performed 3–31 months after injury. Extensile iliofemoral or Y-shaped approach with trochanteric osteothomy was used in most cases. Depending of particular situation a variety of techniques were applied to provide adequate bone stock for the cup, such as an approximate ORIF, periacetabular osteotomy, structural or morcelised bone grafting. Reinforcement ring was used in 6 cases. The cup fixation was cemented in 12 procedures and uncemented in 2. Cemented stem was introduced in 10 cases and uncemented in 4. Preoperative selective embolisation of superior gluteal artery was carried out in 1 patient. RESULTS. The operative duration was 3–7 hours and blood loss was 850–2200 ml. The only intraoperative accidentwas jatrogenic lesion of superior gluteal artery required embolisation. The follow up was a 16–94 months. Average postoperative Harris Hip Score was 78, compared with 54 before surgery (P<0.01). There was 2 aceptic and 1 septic loosenings with subsequent revisions (21.4%). In 2 cases sight asymptomatic migration of the cap was noted. DISCUSSION. The most difficult but most important stage of operation is a creating of sufficiently stable bone stock for the acetabular cap, impeded by by fragment displacement, nonunion or prolonged hip dislocation. If nonuion the achievement of bone healing is essential. Any instability should be overcomed by stable osteosynthesis. The gaps should be filled by ORIF or bone grafting. We consider cemented fixation possibly with reinforcement ring as a most secure way to provide strong cup anchorage. Uncemented pess-fit cup may be used in cases with lesser initial displacement. In spite of all late results are considerable worse than in conventional hip replacement. CONCLUSION. THR after neglected acetabular fractures is a challenging and demanding procedure. Successful outcome may be only expected if a solid bone stock is made using various surgical techniques

Background. Habitual hip subluxation and dislocation is a potentially disabling feature of Trisomy 21. We describe long-term outcomes following precise use of the femoral varus derotation osteotomy to achieve and maintain hip stability and community ambulation. Methods. All individuals with Trisomy 21, who had hip surgery at Toronto's Hospital for Sick Children between 1998 and 2008, were searched using the hospital databases. 16 hips in 9 children aged less than 10 years, were identified. All had a femoral varus derotation osteotomy (VDRO) with a target femoral neck shaft angle (NSA) of 105° and less than 20° external rotation. All were performed by the senior author JHW. The clinical notes and radiographs were reviewed from presentation to final follow up. Continuous variables were assessed for normality with the d'Agostino Pearson test. Normally distributed variables are presented as means with 95% confidence intervals. Pre and postoperative means were compared using the student's t-test for paired samples. Results. Mean age at first known hip dislocation was 4.56 years (3.98, 5.15), mean age at surgery 6.07 years (5.15, 7.0) and mean follow-up 5.4 years (3.75, 7.06). Mean femoral neck shaft angle (NSA) fell from 166.7° (162.2°, 171.1°) to 106.0° (103.1°, 110.2°). In 2 hips, significant intraoperative instability persisted and periacetabular osteotomies with capsulorraphies were required. All patients developed an asymptomatic waddling gait postoperatively. 14 hips developed peritrochanteric varus deformities, mean 20.7° (15.96°, 25.4°)2 (12.5%) sustained periprosthetic fractures 4 and 8 years postoperatively. 1 hip (6.2%) developed painful arthritis. None re-dislocated at latest follow up. Conclusion. Prevention of long term disabling pain from habitually dislocating or recurrently subluxed hips, in patients with Trisomy 21, requires surgical intervention to increase hip containment. We believe surgical management of habitually subluxed or dislocated Trisomy 21 hips allows for a predictable result. We recommend a varus producing proximal femoral osteotomy to correct the NSA to 105° with less than 20° of external rotation. This technique was successful at restoring and maintaining hip stability in 16 hips with a mean follow-up of 5.4 years, whilst maintaining the patient's ability to remain community ambulators. It should be performed before aged 8 or signs of a widened or V-shape teardrop develops. In our experience this has been effective in maintaining hip stability. However, little is known about the natural history of habitual hip dislocation in these children. Patients with Trisomy 21 are living longer with hips that are at continuous risk. Thought should be given to the potential benefits of periodic screening of this treatable hip condition